Variable compressor

ABSTRACT

A variable capacity piston type compressor has a front housing, cylinder housing and rear housing. A rotary shaft may have a first end and a second end. The first end of the rotary shaft may be disposed through and rotatably supported by the front housing. The second end of the rotary shaft may be disposed through the cylinder block. The second end of the rotary shaft may also have a reduced diameter portion and a shoulder portion. A stopper may be inserted over the reduced diameter portion of the rotary shaft and abut the shoulder portion of the rotary shaft.

FIELD

This present disclosure relates to the field of automotive heatingventilation and air conditioning (HVAC) variable displacementcompressors and the assembly thereof.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

The present teachings relate to automobiles and automotive HeatingVentilating and Air Conditioning (HVAC) systems. Air Conditioningsystems generally include a compressor or air conditioning (A/C)compressor or pump to distribute a refrigerant throughout the system.The present teachings relate to a variable type compressor and assemblythereof.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

A variable displacement compressor may comprise a front housing,cylinder housing and rear housing. There may also be a rotary shaft thatmay have a first end and a second end. The first end of the rotary shaftmay be disposed through the front housing. The second end of the rotaryshaft may be disposed through the cylinder block. The second end of therotary shaft may have a reduced diameter portion and may also have ashoulder portion. A stopper may be inserted over the reduced diameterportion and may abut the shoulder portion of the rotary shaft.

Another aspect of the disclosure may be a variable A/C compressor thatmay have a front housing that may form a crank chamber. The compressormay also have a plurality of cylinder bores formed in the cylinderhousing. The compressor may also have a shaft that may have a first endrotatably supported by the front housing and a second end that extendsthrough the cylinder housing. Additionally the valve plate may belocated at an opposite side of cylinder housing from the crank chamber.A selected size stopper may be press fitted over the second end of theshaft and abut a shoulder on the shaft.

Yet another aspect of the present disclosure may be the method ofassembly of the variable displacement compressor. The method may havethe step of inserting the first end of the shaft through the fronthousing. Another step may be inserting the second end of the shaftthrough the cylinder housing. The assembly method may then measure thedistance between the shoulder of the second end of the shaft and therear surfaces of the cylinder housing. The method then may then select aranked stopper from an inventory of sorted and ranked by varying lengthsof the stopper. The method then may press the ranked stopper onto thesecond end of the shaft until the stopper abuts the shoulder of theshaft.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a schematic representation of a vehicle having a HVAC system.

FIG. 2 is diagram of a HVAC system.

FIG. 3 is a cross section view of a variable A/C compressor

FIG. 4 is a exploded view of the second end of the shaft of the variableA/C compressor.

FIG. 5A is a cross section view a compressor during assembly.

FIG. 5B is a cross section view a compressor during assembly.

FIG. 6A is a isometric view of a stopper.

FIG. 6B is a plane view of a stopper.

FIG. 6C is a isometric view of an alternative embodiment stopper.

FIG. 6D is a plane view of an alternative embodiment stopper.

FIG. 7A is a cross section view a compressor during assembly.

FIG. 7B is a cross section view a compressor during assembly.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings. The following description is merely exemplaryin nature and is not intended to limit the present disclosure,application, or uses. It should be understood that throughout thedrawings, corresponding reference numerals indicate like orcorresponding parts and features.

Referring initially to FIG. 1, a vehicle 10 includes an enginecompartment 12 and a HVAC system 14, depicted in dotted lines. HVACsystem 14 may include an air-conditioning compressor 16 in the enginecompartment 12, an HVAC unit 18, that heats or cools the passengercompartment 20. Turning now to FIG. 2, which represents a simpleschematic diagram of a HVAC system 14 will be further explained. Arefrigeration cycle of HVAC system 14 includes compressor 16 whichdraws, compresses, and discharges a refrigerant, such as R134a, 1234YF,CO2, by way of non-limiting example. The power of a vehicle engine 22may be transmitted to compressor 16 through a pulley 24 and a belt 26 toenable compressor 16 to compress the refrigerant.

In HVAC system 14, the compressor 16 discharges a superheated gasrefrigerant at a high pressure, which flows into a condenser 28, whereheat exchange is performed with outside (ambient) air that flows acrossthe condenser represented by arrow 30. The ambient air may be forced bya cooling fan (not shown). The refrigerant is cooled before and duringcondensation. The refrigerant is condensed in condenser 28 and may flowinto a receiver 32. Those skilled in the art will recognize that theHVAC system 14 may be an accumulator or an expansion valve 34 system.The current description is of a T×V system, however the principlestaught in this disclosure may be for either system.

The liquid refrigerant from the receiver 32 is expanded by an expansionvalve 34, also known as a thermal expansion valve or TXV, into agas-liquid double phase state of low pressure refrigerant fluid. The lowpressure refrigerant from TXV 34 flows into an evaporator 36 by way ofan inlet pipe 38. Evaporator 36 is arranged inside HVAC unit 18 of theHVAC system 14. The low pressure refrigerant flowing into evaporator 36absorbs heat from the air 40 inside the HVAC unit 18 as air 40 is passedover evaporator 36. Outlet pipe 42 of evaporator 36 may be connected tothe suction side of compressor 16, so that the refrigeration cyclecomponents mentioned above constitute a closed fluid circuit.

HVAC unit 18 forms a ventilation duct through which air conditioning airis sent into passenger compartment 20. HVAC unit 18 may contain a fan 44that is arranged on the upstream side of the evaporator 36. An fresh orrecirculation air switch housing (not shown) may be arranged on thesuction side of fan 44, that is, the left side of fan 44 in FIG. 2, suchthat the air inside passenger compartment 20 (inside air) or the airoutside passenger compartment 20 (outside air) may be alternated ormixed and introduced through fresh or recirculation air switch housingand into the HVAC unit 18 by fan 44.

HVAC unit 18 accommodates, on the downstream side of evaporator 36, ahot water heater core (heat exchanger) 46, which has an inlet pipe 48and an outlet pipe 50. Hot water (coolant) of vehicle engine 22 isdirected to heater core 46 through inlet pipe 48 by water pump 52. Aradiator 54 and a thermostat 52 further cooperate to control thetemperature of the circulating liquid coolant.

Disposed inside the HVAC unit 18 is an air mix door 56 that adjusts thevolume of air that passes through or bypasses the hot water heater core46. Additionally, a plurality of outlets 58 are formed at the downstreamend of the HVAC unit 18, the outlets 58 may be configured to direct airto different areas of the passenger compartment 20. Outlets 58 may beopened and closed by outlet mode doors (not shown).

With reference now to FIG. 3, compressor 16 is depicted in across-sectional view, the current teachings are in regards to a variabledisplacement compressor. Compressor 16 has a front housing 60, acylinder housing 62 also known as a cylinder block, and a rear housing64, which all may be joined together by a plurality of bolts 66, forexample. The bolts 66 are inserted through the front housing 60 andcylinder housing 62 and are threaded into the rear housing 64 to holdthe assembly together. A shaft 68, also known as a rotary shaft, iscentered in the front housing 60 and passes through the cylinder housing62. The front housing 60 forms an enclosure known as a crank chamber 70.Within the crank chamber 70 a lug plate 72 is attached to the shaft 68.The lug plate 72 is supported against the front housing 60 by a thrustbearing 74, the lug plate 72 and thrust bearing supports the shaft 68 ina front axial direction. A generally disk-shaped swash plate 76 isloosely or pivotably installed around shaft 68 so as to be able tofreely tilt or pivot with respect to the shaft 68, while also contactingshaft 68. The shaft 68 and swash plate 76 may freely rotate within crankchamber 70 and may cause one or more pistons 78 to reciprocate parallelto shaft 68 within the cylinders 80, also may be known as cylinderbores, of the cylinder housing 62. As an example seven pistons 78 may beprovided at equal or unequal intervals around the shaft 68, it is alsoknown in the art that variable displacement compressors may have five orsix pistons.

Continuing with FIG. 3, a plurality of semispherical shoes 82 may fitinto a pair corresponding semispherical recesses that oppose oneanother. The recesses are formed in the end of each piston 78 andfacilitate movement of each piston 78 with a corresponding periphery ofswash plate 76. Alternatively, each semispherical shoe 82 may have flatsurfaces that abut the flat surface of the swash plate 76. An arm 84 maybe attached to and project out and away from lug plate 72. Swash plate76 also has a corresponding arm that further projects out to arm 84 withan arm-like guide 86. The compressor 16 also has a working chamber 88,also known has a compression chamber that is formed by a flat surface orface 90 of piston 78, cylinders 80, and valve plate 92. The workingchamber 88 is for compressing a fluid, such as a refrigerant for anair-conditioning system. A control valve 94 is located in the rearhousing 64. The control valve 94 regulates the angle of the swash plate76 buy controlling the pressure of the crank chamber 70. When pressurein the crank chamber 70 is reduced the swash plate 76 angle increasesand lengthens the stroke of the pistons 78, thus increasing thedisplacement, increasing the volume of the working chamber 88, of thecompressor 16. The rear housing may also have a suction port 96 which isconnected to the outlet pipe 42 of the evaporator to allow refrigerantto flow into the compressor 16. The suction port is fluidly coupled tothe suction chamber 98 enclosed in the rear housing 64. The suction port96 fluidly communicates with working chamber 88 through a series of oneway valves (not shown). Discharge port 100 also is in fluidcommunication with working chamber 88 through a series of one waydischarge valves (not shown).

Further continuing with FIG. 3 the shaft 68, which has a first end 101that is exposed outside the front housing 60 to attach a pulley 24 (FIG.2), and a second end 103 that abuts a selectable stopper 102 to preventaxial movement of the shaft 68 toward the rear housing 64. The stopper102 may abut against the valve plate 92 and may act as a bearing for therear of the shaft 68 during operation of the compressor 16. FIG. 4 is anexploded view of dotted circle A of FIG. 3. The shaft has a shoulder104, or a step, machined or formed into the end of the shaft 68,creating a reduced diameter portion 105 of the shaft, the shoulder 104may also be referred to as shoulder portion 104. The stopper 102 abutsthe shoulder 104 to prevent any movement relative to the stopper 102 andshaft 68. During operation of the compressor 16 the stopper 102generally may contact the valve plate 92. However during assembly, it isrecommended that the dimension D to be maintained at a range 30-90microns (μ). This generally allows for enough stack-up tolerance toprevent the pistons 78 from crashing into the valve plate 92 duringoperation. However, it is not to much clearance as to reduce theefficiency of the compressor 16 overall by causing too much topclearance, which is the distance from the piston face 90 and the valveplate 92 at full compression. To control dimension D to such a tighttolerance the stopper 102 can be selected from a series of length rankedstoppers 102 during the assembly process that will be described in theforgoing description.

The present disclosure discusses the selection process of a ranked orselectable stopper 102. FIG. 5A displays the compressor 16 in a state ofassembly. The compressor 16 sits in an assembly nest 106; the assemblynest has a controlled surface 108 in which a controlled machine surface110 of the front housing 60, shown in FIG. 3, rests upon. The assemblynest 106 may be connected to an assembly conveyor (not shown) to move itto different assembly stations. Measuring tool 112 makes contact withthe shoulder 104 of the shaft 68. FIG. 5B displays measuring tool 112making contact with the rear surface 114 of the cylinder housing 62,rear surface 114 abuts the valve plate 92 when the compressor 16 isfully assembled. Both measurements may be done at separate stationsduring assembly or at the same station. The measurements are received bya computer (not shown) on the assembly line and the computer determinesthe stack up dimension from the shoulder 104 of the shaft 68 and therear surface 114 of the cylinder housing 62. The computer than canselect or indicate which length stopper 102 can be installed on theshaft 68 to maintain the recommended dimension D at a range 30-90microns (μ).

FIGS. 6A-6D displays multiple embodiments of the stopper 102. Generallythe stopper may contain an opening 116 where the reduced diameterportion 105 of the shaft 68 is inserted during assembly. The opening 116may be press fit onto the reduced diameter portion 105 to preventmovement between the shaft 68 and stopper 102. The stopper 102 may alsocontain a flange portion 118, the flange portion provides a surface 120to contact the valve plate 92 (FIG. 3) during operation of thecompressor 16. Additionally, the stopper 102 may have holes (not shown)in the body 122 portion or the flange portion 118. For assembly of thecompressor 16, the length dimension X is used to maintain therecommended dimension D at a range 30-90 microns (μ). The stopper 102 ismanufactured at several different lengths X. The lengths can vary andmay be ranked by length, for instance based on the stack up tolerance ofthe compressor 16; the stopper 102 length may need to vary by 10-20microns (μ) and the assembly process may choose between, for example,five ranked stoppers giving a total range difference of one hundredmicrons (μ). If the computer (not shown) on the assembly line (notshown) measures a large distance between the shaft shoulder 104 and therear surface 114 of the cylinder housing 62, then it would select alarger ranked stopper 102, however if a small distance is measured, thena stopper 102 with a smaller length dimension X will be selected. Thelength and the ranking of the stopper 102 is dependent on the tolerancesof the other components in the compressor 16, it can be appreciated thatif the tolerances on the other components are greatly varied then alarger length dimension range may be needed for the stopper 102. Thestopper 102 may be manufactured by for example, stamping into shape acold rolled steel or stainless steel, then sorted into the variouslengths X. The stopper 102 needs to be formed from a strong enoughmaterial to maintain the dimension D during operation.

Once the proper length stopper 102 is selected with the proper length X.An operator or machine (not shown) may place it on the end of the shaft68, as shown in FIG. 7A. A press 124 will make contact with the stopper102 and press it down axially until the stopper 102 abuts the shaftshoulder 104 as shown in FIG. 7B. The reduced diameter portion 105 andopening 116 create a press fit. The rest of the compressor 16 may befurther assembled.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

What is claimed is:
 1. A variable displacement compressor comprising: afront housing; a cylinder block; a rear housing; and a rotary shaft witha first end and a second end, the first end of the rotary shaft disposedthrough the front housing, the second end of the rotary shaft disposedthrough the cylinder block, the second end of the rotary shaft having areduced diameter portion and a shoulder portion, wherein a stopper isinserted over the reduced diameter portion and abuts the shoulderportion of the rotary shaft.
 2. A variable displacement compressoraccording to claim 1, further comprising a valve plate disposed betweenthe cylinder block and rear housing.
 3. A variable displacementcompressor according to claim 2 wherein the stopper is spaced apart fromthe valve plate at a clearance.
 4. A variable displacement compressoraccording to claim 3, where the clearance is a range between 30-90microns (μ).
 5. A variable displacement compressor according to claim 1,further comprising a swash plate rotated by the rotary shaft, the swashplate disposed on the shaft between the first end and second end.
 6. Avariable displacement compressor according to claim 5 furthercomprising: a plurality of cylinder bores formed in a cylinder housing;and a plurality of pistons disposed in the cylinder bores, wherein thepistons have opposing semispherical recesses formed in an end of theplurality of pistons and a plurality of semispherical shoes fit into thesemispherical recesses, where in the shoes abut the swash plate.
 7. Avariable A/C compressor comprising: a front housing that forms a crankchamber; a plurality of cylinder bores formed in a cylinder housing; ashaft with a first end rotatably supported by the front housing and asecond end that extends through the cylinder housing; a valve platelocated at an opposite side of cylinder housing from the crank chamber;and a selected size stopper fitted over the second end of the shaft andabuts a shoulder on the shaft.
 8. A variable A/C compressor according toclaim 7, further comprising: a rear housing, the rear housing located anopposite side of the valve plate from the cylinder housing.
 9. Avariable A/C compressor according to claim 8, wherein the selected sizestopper has an opening, a body and a flange portion.
 10. A variable A/Ccompressor according to claim 9, wherein the flange of the selected sizestopper is spaced apart from the valve plate at a clearance.
 11. Avariable A/C compressor according to claim 10, wherein the clearance isa range between 30-90 microns (μ).
 12. A method of assembly for avariable compressor, the method comprising: inserting a first end of ashaft through a front housing; inserting a second end of the shaftthrough a cylinder housing; measuring a distance between a shoulder ofthe second end of the shaft and a rear surfaces of the cylinder housing;selecting a ranked stopper from an inventory that is sorted and rankedby varying lengths of the stopper; and pressing the ranked stopper ontothe second end of the shaft until the stopper abuts the shoulder of theshaft.
 13. A method of assembly for a variable compressor according toclaim 12 further comprising: placing valve plate on rear surface ofcylinder block; placing rear housing on valve plate; and inserting boltsthrough front housing, cylinder block, the bolts engaging threads in therear housing.